1. Field of the Invention
The invention relates to a pharmaceutical composition for systemic transdermal administration comprising an active loratidine metabolite as active ingredient.
2. Description of the Related Art
Loratidine (ethyl-[4-(8-chloro-6,11-dihydro-5H-benzo[5,6]cyclohepta[1,2-b]pyridin-11-ylidene)-1-piperidinecarboxylate]) is an antihistamine that is available commercially as syrup or in the form of tablets. The active ingredient is metabolised in the body.
There is now a need to improve the antihistaminic effect and to provide a systemic form of administration. In tests carried out for that purpose, it has, surprisingly, been established that an active loratidine metabolite has sufficient stability to be provided as active ingredient in a pharmaceutical composition for systemic transdermal administration.
The problem underlying the invention is solved by a pharmaceutical composition for systemic transdermal administration that comprises an active loratidine metabolite as active ingredient. The antihistaminic effect of the active loratidine metabolite can be exploited for that pharmaceutical composition.
A loratidine metabolite can be obtained from Irotec Laboratories (County Cork, Ireland) and has the following formula: 
According to the invention, the pharmaceutical composition can be provided in the form of a customary liquid or solid form of systemic transdermal administration. For the relevant prior art, see, for example, DE-A-3 212 053, GB-A-2 098 865, Remington""s Pharmaceutical Sciences, 16th edition, Mack-Verlag, and Sucker, Fuchs and Spieser, Pharmazeutische Technologie, 1st edition, Springer-Verlag.
The pharmaceutical composition according to the invention is customarily in the form of a viscous liquid, an ointment, a composition having a reservoir or a composition having a matrix. For example, the active loratidine metabolite may be present in a reservoir or matrix which are provided in the form of a gel or a polymer, for example in the form of a polymer according to EP-A-0 155 229.
According to a special embodiment, the pharmaceutical composition according to the invention may have a transdermal patch structure.
According to the invention, the patch structure can be provided by an acrylate-based matrix formed in customary manner on a carrier layer that is impermeable to water, it being possible to provide additionally a removable cover layer that protects the matrix.
According to the invention, the material of the matrix may be a non-swellable acrylate polymer, for example Durotack 280-2416 (Delft National Chemie, Zotphen, Netherlands).
The invention is explained hereinafter in greater detail by way of example.
In vitro test
A diffusion test is carried out in vitro according to Franz in J. Invest. Dermatol., 64 (1975) 194-195 and GB-A-2 098 865. For the test, the active loratidine metabolite is applied to one side of an isolated intact segment of mouse skin having a surface area of 2.5 cm2. The other side of the skin segment is placed in contact with a 0.9% sodium chloride solution additionally containing 0.05% sodium azide. The amount of active ingredient that passes into the salt solution is monitored in customary manner by HPLC (HP Liquid Chromatography). Details are given below.